When a bro emerges from his pupal state into a fully formed bro. The fully formed bro stage usually has different morphological features, depending on the environment of the bro in question. This change of life stage is brought on by varying environmental cues, such as the music of the Dave Matthews Band or the emmersion of the pupa into Natty Ice.

Upon hearing Ants Marching by DMB, the bro emerges from his pupa, fully formed with red plastic cup in hand and sideways cap on his head, his metabrophosis complete.